Question regarding AES

I know that im suppose to plug in the equations into some of my beers law formulas but the question given says that in one test the AES readings were below the detection limit. Should I put in a 1 or a 0 for that part of the formula if the readings were below detection limit?

2. Relevant equations

3. The attempt at a solution
I would assume that you are to put 1 in for this value as to avoid having a zero in the denominator and/or multiplying the whole equation by zero... but who knows.